[en] Mutation for vertical mildew resistance did not seem to be promising under our environmental conditions. Occasionally, we detected moderately disease resistant types in the M₃ and M₄. However, the rate of mutations for moderate type of resistance for five diseases was indeed lower in the irradiated populations than in the non-irradiated ones. On the other hand, in the production of characters which used to be considered as non-progressive from an evolutionary point of view /e.g. dwarfness/, induced mutations seemed to be superior over spontaneous mutations. The usefulness of three methods for screening large mutant populations for race non-specific disease resistance, namely the Tolerance Test, the Multitolerance Test and the Center Pivot Method is discussed. Regarding the biochemical nature of rust resistance, we came to the conclusion that the so called common antigens correlate compatibility between the host and the pathogen only on a species level. However, the ''common antigen theory'' i.e. the occurrence or the lack of common antigenic proteins in host and pathogen does not offer an explanation for susceptibility or resistance, respectively on a cultivar level. (author). (author). (author)